Tag: 1Z0-051 Practice Test

QUESTION 1
Evaluate the following CREATE TABLE commands:
CREATE TABLE orders
(ord_no NUMBER(2) CONSTRAINT ord_pk PRIMARY KEY,
ord_date DATE,
cust_id NUMBER(4));
CREATE TABLE ord_items
(ord_no NUMBER(2),
item_no NUMBER(3),
qty NUMBER(3) CHECK (qty BETWEEN 100 AND 200),
expiry_date date CHECK (expiry_date > SYSDATE),
CONSTRAINT it_pk PRIMARY KEY (ord_no,item_no),
CONSTRAINT ord_fk FOREIGN KEY(ord_no) REFERENCES orders(ord_no));
The above command fails when executed. What could be the reason?

A.    SYSDATE cannot be used with the CHECK constraint.
B.    The BETWEEN clause cannot be used for the CHECK constraint.
C.    The CHECK constraint cannot be placed on columns having the DATE data type.
D.    ORD_NO and ITEM_NO cannot be used as a composite primary key because ORD_NO is also
the FOREIGN KEY.

Answer: A
Explanation:
CHECK Constraint
The CHECK constraint defines a condition that each row must satisfy. The condition can use the same constructs as the query conditions, with the following exceptions:
References to the CURRVAL, NEXTVAL, LEVEL, and ROWNUM pseudocolumns Calls to SYSDATE, UID, USER, and USERENV functions
Queries that refer to other values in other rows
A single column can have multiple CHECK constraints that refer to the column in its definition. There is no limit to the number of CHECK constraints that you can define on a column. CHECK constraints can be defined at the column level or table level.
CREATE TABLE employees
(…
salary NUMBER(8,2) CONSTRAINT emp_salary_min
CHECK (salary > 0),

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